JPH0437868A - Image forming device - Google Patents

Abstract

PURPOSE:To start the feeding of a sheet from an inversion means without having an instruction from an operating side by providing a paper passing control means selecting a paper ejecting part except the inversion means, as a paper ejecting means, when the inversion means is selected as a paper feeding means. CONSTITUTION:When a double-side carrying part is selected as a paper ejecting port, the sheet is fed from a paper feeding cassette 1 or 2, printed by an image forming process equipment, and then, fed to the inversion switching part 24 of the double-side carrying part by the switching of a separating nail 23. Then, a separating lug, 30 is switched and simultaneously, an inversion roller 27 is reversely rotated, so that the sheet is carried to an inversion paper standby part 25. When a command that the double-side carrying part is selected as a paper feeding port is carried out, first, it is judged whether the sheet is on standby or not on the inversion paper standby part 25, by an inversion paper presence detecting sensor 31, and next, the double-side carrying part is selected as the paper feeding port. When the double-side carrying part is selected as the paper ejecting port, a prescribed paper ejecting tray 3 or 4 except the double-side carrying part is selected as the paper ejecting port. Then, the sheet in standby is fed on the inversion paper standby part 25, and on a paper ejecting tray after its other surface has image forming processing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to image forming apparatuses such as laser printers and copying machines.

[Conventional technology]

An image forming apparatus such as a laser printer includes a paper feeding section that feeds paper, a paper ejection section that ejects the paper after image forming processing, and a reversing unit that inverts the paper after image forming processing. In some cases, the reversing means can be selected as the paper feeding means or the paper discharging means.

In such image forming apparatuses, it is generally possible to select the reversing means as the paper feeding means and the paper ejecting means at the same time, so if such simultaneous selection is made, the reversing means does not have the paper. Even if there was a paper feed, control was performed to prevent paper feeding from starting from that point.

[Problem to be solved by the invention]

However, in such paper feeding control, in order to start paper feeding from the reversing means when the above-mentioned simultaneous selections are made, the operator must then select a paper ejecting means other than the reversing means as the paper ejecting means. Since it is necessary to re-select the copy, there is a problem in that not only does the burden on the operator increase, but also printing work is hindered.

This invention has been made in view of the above points, and even if the reversing means is selected as a paper feeding means and a paper ejecting means at the same time, it is possible to feed paper from the reversing means without receiving instructions from the operator. The purpose is to

(Means for Solving Problem W) In order to achieve the above object, the present invention provides an image forming apparatus such as the one described above, in which when the reversing means is selected as the paper feeding means, the reversing means is used as the paper ejection means. A sheet passing control means for selecting a sheet discharge section other than the sheet discharge section is provided.

Furthermore, the reversing means may be provided with a paper presence/absence detection means for detecting the presence or absence of paper, and a means for prohibiting selection of the reversing means as the paper feeding means when the paper is detected to be out of paper by the means. desirable.

[For production]

According to the image forming apparatus according to the present invention, when the reversing means is selected as the paper feeding means, even if the reversing means is also selected as the paper ejecting means at this time, the paper passing control means is used as the paper ejecting means. Since the paper ejection section other than the reversing means is reselected, paper feeding from the reversing means can be started without receiving instructions from the operating side.9 Therefore, not only the burden on the operating side is reduced, but also
There will be no hindrance to printing work.

Furthermore, if the reversing means is provided with a paper presence/absence detection means for detecting the presence or absence of paper, and if it is detected that there is no paper, the reversing means is prohibited from being selected as a paper feeding means. Paper feeding can be started only when there is paper, which is advantageous.

〔Example〕

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 2 is a schematic diagram showing the mechanism of a laser printer according to an embodiment of the present invention, and the paper passing path is shown by a broken line with an arrow.

This laser printer is removably equipped with two upper and lower paper feed cassettes 1゜2 each capable of storing 250 sheets of cut paper, and also has a first paper output tray 3 at the top and a second paper output tray 4 at the rear. Each is provided.

Furthermore, inside this printer, there is a photoconductor (○PC) drum 5, which constitutes an image forming section. Charger 6, optical scanning device (laser writing device) 7. Developing equipment! 8° Transfer charger 92 Separate charger 10. Cleaning unit 11.
and a fixing device 12.

In addition, the pre-feed rollers 13, 14 and the feed roller 15.1
6.17, a paper feeding conveyance section consisting of a registration roller 18, a registration sensor 19, etc., a paper ejection conveyance section consisting of conveyance rollers 20, 21, a paper discharge roller 22, a branch claw 23, etc., and a reversal switching section 24. Reversing paper special unit 25 and conveyance roller 269 Reversing roller 27° Double-sided transfer roller 281 Double-sided paper feeding roller 2
9, a branching claw 30, a reversing paper presence/absence detection sensor 31, and an opening conveying section as a reversing means.

Note that the paper feed rollers 15 and 16 are designed so that the lower roller (separation roller) rotates in the reverse direction when feeding paper in order to prevent double feeding of paper fed from the paper cassette 1.2. .

Furthermore, a board (electrical transmission system board) for a control section 32 that controls the laser printer is mounted above the inside of the printer.

Here, the operation of each of the above parts will be briefly explained.

When the print sequence is started by the control unit, at a predetermined timing, the pre-feed roller 13, the pre-feed roller 15, or the pre-feed roller 14. Paper feeding begins with the paper feeding roller 16,
The paper is stopped when the leading edge of the paper is detected by the registration sensor 19 and a predetermined time has elapsed. As a result, the paper is placed on standby with its leading end being held between the registration rollers 18.

On the other hand, the photosensitive drum 5 rotates in the direction of the arrow in FIG.
7, a laser beam modulated according to the video data is irradiated while main scanning in the direction of the drum axis for exposure.
A potential difference is generated between the irradiated portion and the irradiated portion to form an electrostatic latent image.

The latent image is uniformly applied to the developing roller 8a by the developing device f8.
The toner on the toner is adhered and developed, and transferred by the transfer charger 9 onto a sheet of paper that is re-fed by the registration rollers 18 at a predetermined timing.

Then, the transferred paper is peeled off from the photosensitive drum 5 by the action of the separation charger 10 and fixed! 12, the sheet is heated for fixing, and then the sheet that has been heated for fixing is sent to a paper discharge section.

At this time, the paper is output to the selected output tray, either the first output tray 3 located at the top of the printer or the second output tray 4 located at the rear of the printer, via the paper output transport section. It is papered.

Note that although the first paper ejection tray 3 is normally selected, the second paper ejection tray 4 is selected in special cases, such as when paper that tends to curl, such as envelopes and postcards, is used.

By the way, when double-sided printing is selected, the conveying path of the paper printed on one side is changed to the direction of the conveying section for double-sided printing by the branch claw 23, and the reversing switch for double-sided printing is performed by the conveying roller 26 and the reversing roller 27. Part 24
When the trailing edge of the sheet passes through the branching claw 30, the sheet is temporarily stopped.

Then, while switching the branching claw 30, the reversing roller 27
1, reverse the paper feeding direction, and transfer the paper to the double-sided transfer roller 28.
The paper is also rotated and conveyed to the reversing paper special unit 25, and stopped when the leading edge reaches the double-sided paper feed roller 29.

Thereafter, at a predetermined timing, the paper is re-fed toward the registration rollers 18 by the duplex feed roller 29 and the duplex transfer roller 28, printed on the other side in the same manner as described above, and then ejected to one of the paper ejection trays. Paper.

In this embodiment, the first paper feed tray 1 is used as the paper feed port.
．． Either the second paper feed tray 2 or the duplex transport unit is used as the paper ejection outlet.
Alternatively, it is possible to select one of the two-sided conveyance sections.

FIG. 3 is a block diagram showing the control section 32 of FIG. 2. As shown in FIG.

This control unit 32 functions as a controller that creates page-by-page video data based on various data such as character code data and control instructions (hereinafter referred to as "commands") from the host computer 40, and the functions of The engine driver functions as an engine driver that controls the image forming process equipment shown in FIG. 2 for printing characters and the like on paper based on video data and commands.

Specifically, the CPU 4 deciphers various commands, executes various processes, and centrally controls the entire print control section.
1, a ROM 42 that stores a processing program for operating this CPU 41, a RAM 43 that stores created video data, etc., and various types including a registration sensor 19 and a reversal paper presence/absence detection sensor 31 shown in FIG. An input port 44 for inputting signals from sensors and switches 48, and for outputting control signals to sequence equipment 49 such as the optical scanning device 17, solenoids for switching each branch claw 23, 30, etc., and various motors. output boat 45
, an input buffer 46 that temporarily stores data input from an interface circuit 47, and an interface circuit 47 that receives and inputs data from a host computer 40 such as a word processor or personal computer (Centronics, R5-232C, etc.) )
These are interconnected by a path line 50 consisting of an address bus, a control bus, and a data bus.

Next, various commands sent from the host computer 40 will be explained.

It is the host computer 40 that gives image processing instructions to this laser printer.
Commands are sent from 0 to 1 byte (8 bits).

Among these commands, the command FF according to this invention
, VT, and A-F are shown below.

1. Command FF is a command for starting paper feeding and stopping it when a predetermined time has elapsed since the leading edge of the paper was detected by the registration sensor 19 (when the leading edge of the paper reached the registration roller 18).

2. Command VT is a command for restarting the conveyance of the paper that has stopped with its leading end being held by the registration rollers, and for printing.

3. Command A is a command for selecting the first paper feed cassette 1 as the paper feed port (paper feed section).

4. Command B uses the second paper feed cassette 2 as the paper feed port.
This is a command to select.

5. Command C is a command for selecting the duplex transport section as the paper feed port.

6. Command D is a command for selecting the first paper discharge tray 3 as the paper discharge port (paper discharge section).

7. Command E is a command for selecting the second stray paper tray 4 as the paper discharge outlet.

8. Command F is a command for selecting the double-sided transport unit as the paper discharge port.

Next, the operation of this embodiment configured as described above will be specifically explained with reference to FIG. 1 as well.

After this laser printer is powered on, when it receives commands A and F from the host computer 40, it selects and sets the first paper feed cassette 1 as the paper feed port and the double-sided transport section as the paper discharge port.

After that, when commands FF and VT are received, paper feeding is started from the first paper feeding cassette 1 at a predetermined timing, and the leading edge of the paper is detected by the registration sensor 19, and the paper is temporarily stopped after a predetermined time.

Thereafter, the registration roller 18 restarts conveyance of the waiting paper at a predetermined timing, and after the paper is printed by the above-mentioned image forming process equipment, the double-sided conveyance is started by switching the branch claw 23. The trailing edge of the paper is fed into the reversal switching section 24 of the
Pause when it passes 0.

Then, while switching the branching claw 30, the reversing roller 27
The paper is reversed and conveyed to the reversing paper special unit 25, and stopped when the leading edge of the paper reaches the double-sided paper feed roller 29.

Here, upon receiving the command C from the host computer 40, the CPU 41 shown in FIG. 3 executes the paper passing control shown in FIG.

That is, the routine shown in the figure starts when called by the main routine upon reception of command C, and first judges whether or not the reverse paper presence/absence detection sensor 31 is in the ON state. Therefore, after receiving the received command C, it is determined whether the duplex transport unit is selected as the paper feed port.

If the double-sided transport section has already been selected as the paper feed port at this time, the process returns to the main routine, and if it has not been selected as the paper feed port, it is selected as the paper feed port.

Next, it is determined whether or not the duplex transport section is selected as the paper ejection port. However, at this point, it is still selected as the paper ejection port, so a predetermined ejection port other than the duplex transport section is selected as the paper ejection port. A paper tray (for example, the first paper discharge tray 3) is selected and the process returns to the main routine.

If the duplex transport section is not selected as the paper ejection port, the process returns directly.

On the other hand, if the reverse paper presence/absence detection sensor 31 is not in the ON state, command C is rejected.

After prohibiting selection of the duplex conveyance unit as a paper feed port, the process returns to the main routine.

Thereafter, by receiving commands FF and VT from the host computer 40, the double-sided paper feed roller 29 and the double-sided transfer roller 28 are driven again at a predetermined timing, and the paper waiting in the reversing paper special unit 25 is transferred. The paper is re-fed toward the registration rollers 18, and the other side is subjected to the image forming process in the same manner as described above, and then the paper is ejected to one of the selected paper ejection trays.

As described above, in this embodiment, when the duplex transport section is selected as the paper feed port, even if the duplex transport section is also selected as the paper ejection port at the same time, the duplex transport section is selected as the paper ejection port. The paper output tray other than the transport section is automatically reselected so that paper can be fed immediately from the reversing means, reducing the burden on the operator and eliminating any hindrance to printing operations. .

In addition, the reversing paper presence/absence detection sensor 31 is used to determine whether or not there is paper in the special unit for reversing, and paper can be fed from there only when it is confirmed that there is paper, making it more effective. be.

Although an embodiment in which the present invention is applied to a laser printer has been described, the present invention is applicable not only to other optical printers such as LED printers and liquid crystal shutter printers, but also to dot printers such as wire dot printers, thermal printers, and inkjet printers. It can also be widely applied to image forming apparatuses such as digital copying machines and facsimile machines.

〔Effect of the invention〕

As explained above, in the image forming apparatus according to the present invention, even when the reversing means is selected as the paper feeding means and the paper discharging means at the same time, it is possible to feed paper from the reversing means.
The burden on the operating side is reduced, and printing operations are not hindered.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing paper feeding control when command C is received by the CPU 41 in FIG. FIG. 3 is a block configuration diagram showing a control section thereof as well. l...First paper feed cassette 2...Second paper feed cassette 3...First paper output tray 4...Second paper output tray 2
5... Reversing paper special equipment section 31... Reversing paper presence/absence detection sensor 32... Control section 4o... Host computer 41... CPU 42... R'OM FIG.

Claims (1)

[Scope of Claims] 1. A paper feed unit that feeds paper, a paper discharge unit that discharges the paper after image forming processing, and a reversing unit that reverses the paper after image forming processing, the reversing unit In an image forming apparatus in which the reversing means is selected as the paper feeding means or the paper ejecting means, a paper ejecting section other than the reversing means is selected as the paper ejecting means. An image forming apparatus comprising a paper control means. 2. The image forming apparatus according to claim 1, wherein the reversing means is provided with paper presence/absence detection means for detecting the presence or absence of paper, and when the paper absence is detected by the means,
An image forming apparatus comprising: means for prohibiting selection of the reversing means as a paper feeding means.